Semiconductor device and bump formation process

A semiconductor device, comprising:

• a semiconductor substrate;
• a conductive pad over the semiconductor substrate;
• a conductive bump over the conductive pad;
• a conductive cap over the conductive bump;
• a barrier layer having a first portion extending substantially along a bottom surface of the conductive cap and a second portion extending substantially along sidewalls of a bottom portion of the conductive cap;
• and
• a passivation layer over the semiconductor substrate and surrounding the conductive bump.

A semiconductor device, comprising:

• a semiconductor substrate;
• a conductive pad over the semiconductor substrate;
• a conductive bump over the conductive pad and having a first portion and a second portion over the first portion, wherein the second portion has a width smaller than a width of the first portion;
• a conductive cap over the conductive bump;
• and
• a passivation layer over the semiconductor substrate and surrounding the conductive bump.